Invasion of the earthworms

EARTHWORMS’ BENIGN image as aerators, drainers and fertilisers of field and garden belies a darker secret. They are actually fierce competitors with other invertebrates, voraciously consuming rotting plant matter and tiny organisms such as protists, nematodes, bacteria and fungi, all of which might otherwise sustain a wide variety of soil dwellers.That much is well known, not least from research conducted in northern North America. Here, worms were wiped out during the last ice age, which ended 12,000 years ago. They started returning, in the form of European interlopers, only a few centuries in the past. What have not been investigated much until now are the consequences of this subterranean carnage for surface-dwelling critters. But that has just been corrected by Malte Jochum of Leipzig University, in Germany, and his colleagues, in a study just published in .